The present invention regards a structure for electrically connecting microelectromechanical devices, in particular microactuators for hard disk drivers.
As is known, with the advent of new microactuating devices for hard disk drivers, the problem has arisen to devise an effective method for carrying the signal from the head (which is moving) to a fixed point located, for example, on the suspension.
For this purpose, electrical connections of a conductive material, generally metal, are used so as to ensure a low mechanical as well as electrical resistance.
In particular, the connection must not modify the mechanical resistance of the system including the head and the microactuating device and, specifically, the torsional resistance of the movable part of the microactuating device with respect to the fixed part. In fact, the movable part of the microactuating device (rotor) is connected to the fixed part via suspension regions called xe2x80x9cspringsxe2x80x9d and, in general terms, the overall mechanical resistance of the system is affected both by the resistance of the springs and by the resistance of the electrical connections. Since the processes for forming the springs and the electrical connections are generally very different, in the worst case the overall mechanical resistance of the system may be equal to the sum of the two resistances.
Ideally, the mechanical resistance of the connections should be negligible as compared to that of the springs, which are sized so as to bestow on the entire microelectromechanical system the desired torsional rigidity. With current solutions, this, however, is not possible.
An embodiment of the present invention includes a structure for electrically connecting movable and fixed parts of a microelectromechanical device that overcomes the above problem.
According to an embodiment the present invention, a microelectromechanical device is provided with an electrical connection structure that includes connection elements which electrically connect a movable part to a fixed part of a microelectromechanical device, for example a microactuator. The movable part and fixed part are separated by trenches and are mechanically connected by spring elements, which together with the connection elements determine the structural rigidity of the microelectromechanical device. Each connection element is formed by multiple sub-arms connected in parallel and having a common movable anchorage region anchored to the movable part, and a common fixed anchorage region anchored to the fixed part, such that the mechanical resistance of the connection elements is negligible. The sub-arms have a width equal to a sub-multiple of the width necessary for a single connection element to have a predetermined electrical resistance, as determined by the design; i.e., the width of the sub-arms is equal to the width of the single connection element divided by the number of sub-arms. In particular, the width of the sub-arms is at least equal to the width of the single connection element divided by the number of sub-arms.